Abstract

The reaction of amides RSO2-Pro-NHMe with ClCH2SiMe2Cl in the presence of (Me3Si)2NH gave pentacoordinated chlorosilanes RSO2-Pro-N(Me)CH2SiMe2Cl with an organosulfonyl group (R = Me, Ph, 4-ClC6H4, 4-BrC6H4, 4-MeC6H4, and 4-O2NC6H4) attached to the proline nitrogen atom. An alternative method for the preparation of these compounds comprises the cyclosilylmethylation of proline methylamide by dimethylchloromethylchlorosilane to give the previously unreported heterocyclic 2-sila-5-piperazinone system in the first step. The bicyclic silacyclane synthesized is 2-sila5-piperazinone condensed with a proline residue. The action of sulfonyl chlorides RSO2Cl leads to cleavage of the sila ring Si-N bond to give the desired chlorosilanes. The hydrolysis of these products, depending on the reaction conditions, gives either silyloxonium chlorides [RSO2-ProN(Me)CH2SiMe2OH2]Cl or disiloxanes [RSO2-Pro-N(Me)CH2SiMe2]2O. X-ray diffraction structural analysis showed that the silicon atom in the chlorides and silyloxonium chlorides is pentacoordinated due to an intramolecular O→Si bond and has distorted trigonal-bipyrimidal configuration. Si-29 NMR spectroscopy showed that the disiloxanes and bicyclic sila-5-piperazinone have a tetracoordinated silicon atom.